Synthetic jet embedded heat sink

ABSTRACT

A system and method for cooling heat-producing devices using synthetic jet embedded heat sinks is disclosed. The cooling system includes a heat sink comprising a base portion and a plurality of fins disposed on the base portion and extending vertically out therefrom, the plurality of fins spaced to define a channel between adjacent fins. The cooling system also includes at least one synthetic jet actuator attached to the heat sink, with each of the at least one synthetic jet actuators comprising a plurality of orifices therein and being configured to generate and project a series of fluid vortices out from the plurality of orifices and toward at least a portion of the channels of the heat sink.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional of and claims priority to U.S.application Ser. No. 12/261,478, filed Oct. 30, 2008, the disclosure ofwhich is incorporated herein.

BACKGROUND OF THE INVENTION

Embodiments of the invention relate generally to thermal managementsystems and, more particularly, to an apparatus and method for coolinghigh power-density, heat-producing devices using synthetic jet embeddedheat sinks.

Cooling of heat-producing devices is a concern in many differenttechnologies. Particularly in microprocessors, the rise in heatdissipation levels associated with increasingly powerful processingsystem has resulted in the need for new cooling solutions beyondconventional thermal management techniques. This has led to an increaseddemand for advanced and robust cooling solutions with severe volumeconstraints. In the microelectronics industry, for example, advances intechnology have brought about an increase in transistor density andfaster electronic chips. As electronic packages increase in speed andcapability, the heat flux that must be dissipated to maintain reasonablechip temperatures has also risen.

One conventional means for dissipating heat is by way of a heat sink,which can be placed on an electronic package to draw heat awaytherefrom. While air-cooling under natural convection conditions by wayof a heat sink is the simplest possible way to cool a high heat fluxdevice, high power dissipation requirements often necessitate the use offans. Typically, these fans are placed either directly on the heat sinkor are positioned to drive airflow through the heat sink by way of aduct in the heat sink. While fans have the capacity to move asubstantial volume of air, they are noisy, unreliable, and generallyvery inefficient in terms of the heat removed for a given electricalinput power.

Arrays of air-jets have also been used in cooling applications as analternative to fans. However, conventional air-jets are not very usefulfor consumer products, due to requirements of pressure supplies andconduits for directing the air to the heat sink. This makes design ofthe cooling system too complex and the cost of the cooling system toohigh for consumer product applications.

Accordingly, there is a need for a system and method for coolingheat-producing devices in an efficient manner. There is a further needfor such a system to have minimal space requirements and a simplified,cost-effective design.

BRIEF DESCRIPTION OF THE INVENTION

Embodiments of the invention overcome the aforementioned drawbacks byproviding a system and method for cooling high power-density,heat-producing devices using synthetic jet embedded heat sinks. Thesynthetic jet embedded heat sinks provide a compact, reliable mechanismfor cooling having a small footprint. The synthetic jet embedded heatsinks further have a high flux and provide an efficient system forair-cooling heat-producing devices.

In accordance with one aspect of the invention, a cooling systemincludes a heat sink comprising a base portion and a plurality of finsdisposed on the base portion and extending vertically out therefrom, theplurality of fins spaced to define a channel between adjacent fins. Thecooling system also includes at least one synthetic jet actuatorattached to the heat sink, with each of the at least one synthetic jetactuators comprising a plurality of orifices therein and beingconfigured to generate and project a series of fluid vortices out fromthe plurality of orifices and toward at least a portion of the channelsof the heat sink.

In accordance with another aspect of the invention, a method of coolinga heat generating device includes the steps of providing a heat sinkcomprising a plurality of fins positioned to define a plurality ofchannels in the heat sink, attaching a synthetic jet actuator to theplurality of fins, the synthetic jet actuator having a plurality oforifices formed therein, and generating a series of fluid vortices fromthe synthetic jet actuator. The method also includes the step ofprojecting the series of fluid vortices out from the plurality oforifices of the synthetic jet actuator and toward the plurality of finsand channels of the heat sink, wherein the series of fluid vortices areprojected out from the plurality of orifices toward the plurality offins and channels of the heat sink at a plurality of angles.

In accordance with yet another aspect of the invention, a cooling systemincludes a heat sink comprising a base portion and a plurality of finsdisposed on the base portion and extending vertically out therefrom todefine a plurality of channels, wherein the plurality of fins arepositioned on the base portion to surround a central channel. Thecooling system also includes a synthetic jet actuator integrallyattached to the heat sink and positioned in the central channel, thesynthetic jet actuator further including a chamber having wallsenclosing a volume, a plurality of orifices formed in the walls, and anactuator element coupled to at least one of the walls to selectivelycause deflection thereof, thereby changing a volume within the chamberso that a series of fluid vortices are generated and projected out fromthe plurality of orifices and toward the plurality of channels of theheat sink.

These and other advantages and features will be more readily understoodfrom the following detailed description of preferred embodiments of theinvention that is provided in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate embodiments presently contemplated for carryingout the invention.

In the drawings:

FIG. 1 is a cross-section of a prior art zero net mass flux syntheticjet actuator with a control system.

FIG. 2 is a cross-section of the synthetic jet actuator of FIG. 1depicting the jet as the control system causes the diaphragm to travelinward, toward the orifice.

FIG. 3 is a cross-section of the synthetic jet actuator of FIG. 1depicting the jet as the control system causes the diaphragm to traveloutward, away from the orifice.

FIG. 4 is an illustration of a synthetic jet actuator for use with acooling system, according to an embodiment of the invention.

FIG. 5 is an illustration of a synthetic jet actuator for use with acooling system, according to another embodiment of the invention.

FIG. 6 is a cross-section of the synthetic jet actuator of FIG. 5.

FIG. 7 is an illustration of a cooling system according to an embodimentof the invention.

FIGS. 8A-8C are illustrations of a cooling system according to anotherembodiment of the invention.

FIG. 9 is an illustration of a cooling system according to anotherembodiment of the invention.

FIG. 10 is a top view of a heat sink for use with a cooling system,according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-3, a synthetic jet actuator 10 as known in the art,and the operation thereof, is shown for purposes of describing thegeneral operation of a synthetic jet actuator. The synthetic jetactuator 10 includes a housing 11 defining and enclosing an internalchamber 14. The housing 11 and chamber 14 can take virtually anygeometric configuration, but for purposes of discussion andunderstanding, the housing 11 is shown in cross-section in FIG. 1 tohave a rigid side wall 12, a rigid front wall 13, and a rear diaphragm18 that is flexible to an extent to permit movement of the diaphragm 18inwardly and outwardly relative to the chamber 14. The front wall 13 hasan orifice 16 of any geometric shape. The orifice diametrically opposesthe rear diaphragm 18 and connects the internal chamber 14 to anexternal environment having ambient fluid 39.

The flexible diaphragm 18 may be controlled to move by any suitablecontrol system 24. For example, the diaphragm 18 may be equipped with ametal layer, and a metal electrode may be disposed adjacent to butspaced from the metal layer so that the diaphragm 18 can be moved via anelectrical bias imposed between the electrode and the metal layer.Moreover, the generation of the electrical bias can be controlled by anysuitable device, for example but not limited to, a computer, logicprocessor, or signal generator. The control system 24 can cause thediaphragm 18 to move periodically, or modulate in time-harmonic motion,and force fluid in and out of the orifice 16. Alternatively, apiezoelectric actuator could be attached to the diaphragm 18. Thecontrol system would, in that case, cause the piezoelectric actuator tovibrate and thereby move the diaphragm 18 in time-harmonic motion.

The operation of the synthetic jet actuator 10 is described withreference to FIGS. 2 and 3. FIG. 2 depicts the synthetic jet actuator 10as the diaphragm 18 is controlled to move inward into the chamber 14, asdepicted by arrow 26. The chamber 14 has its volume decreased and fluidis ejected through the orifice 16. As the fluid exits the chamber 14through the orifice 16, the flow separates at sharp orifice edges 30 andcreates vortex sheets 32 which roll into vortices 34 and begin to moveaway from the orifice edges 30 in the direction indicated by arrow 36.

FIG. 3 depicts the synthetic jet actuator 10 as the diaphragm 18 iscontrolled to move outward with respect to the chamber 14, as depictedby arrow 38. The chamber 14 has its volume increased and ambient fluid39 rushes into the chamber 14 as depicted by the set of arrows 37. Thediaphragm 18 is controlled by the control system 24 so that when thediaphragm 18 moves away from the chamber 14, the vortices 34 are alreadyremoved from the orifice edges 30 and thus are not affected by theambient fluid 39 being drawn into the chamber 14. Meanwhile, a jet ofambient fluid 39 is synthesized by the vortices 34 creating strongentrainment of ambient fluid drawn from large distances away from theorifice 16.

Referring now to FIG. 4, a synthetic jet actuator 40 for use with anembodiment of the invention is shown. According to the embodiment,synthetic jet actuator 40 is configured as a disc-shaped synthetic jetactuator that includes a wall structure 42 having an unbroken, orcontinuous outer bounding surface or wall 44, having generallycylindrical profile, along with a top surface or wall 46 and a bottomsurface or wall 48. Thus, a generally disc-shaped jet actuator 40 isformed having an enclosed volume, chamber or cavity 50 that is separatefrom the environment 51 external to the volume 50.

As shown in FIG. 4, synthetic jet actuator 40 includes one or moreactuator elements, micromechanical devices, or piezomotive devices 52that are positioned on one or all surfaces 44, 46, 48. Outer surface 44and top surface 46 are shown as having actuators 52 attached thereto.Although actuators 52 are illustrated as covering only a portion of therespective surfaces 44, 46, embodiments of the invention include one ormore actuators 52 configured to cover the entire respective surfaces 44,46, 48 on which they are placed. Actuators 52 may be activated byapplication of a rapidly alternating voltage that causes the actuators52 to rapidly expand and contract and may be monomorph or bimorphdevices. A control system 53 is coupled to actuators 52, and it isrecognized that each actuator 52 includes a control system (not shown)for activation. Further, it is recognized that one control system 53 maybe used to actuate more than one actuator 52.

In embodiments of the invention, actuators 52 may include devices otherthan piezoelectric motive devices such as shape-memory alloys, magneticmaterials, electrostatic materials, hydraulic materials, and ultrasonicmaterials. Thus, in such embodiments, control system 53 is configured toactivate actuators 52 in corresponding fashion. That is, for anelectrostatic material, controller 53 may be configured to provide arapidly alternating electrostatic voltage to actuators 52 in order toactivate and flex surfaces 44, 46, 48 to which actuators 52 areattached. Such additional materials may themselves be configured inmonomorph and bimorph arrangements.

As further shown in FIG. 4, orifices 54 are formed within outer surface44 and are positioned in order to direct fluid emitting therefrom (basedon activation of actuators(s) 52) at desired locations and at an object(not shown) positioned proximate to or around the synthetic jet actuator40. That is, orifices 54 can be dispersed about an outer perimeter 56 ofsynthetic jet actuator 40 (i.e., outer surface 44), to emit fluid at anumber of different angles. The orifices 54 could, for example, belocated at every 45 degrees or every 90 degrees around the outer surface44, so as to provide uniform and circumferential cooling to theobject/component by way of the plurality of orifices 54.

Although the synthetic jet actuator 40 of FIG. 4 is illustrated having adisc shape, the invention described herein is not limited thereto. Oneskilled in the art will recognize that the synthetic jet actuator 40 isnot limited to a disc shape, but could also be shaped as an oval, asquare, a rectangle, an ellipse, and the like, depending on theapplication, and orifices 54 may be positioned accordingly, depending onthe convective cooling and placement requirements of the application.

Referring now to FIG. 5, a synthetic jet actuator 60 for use withanother embodiment of the invention is shown. According to theembodiment, synthetic jet actuator 60 is configured as a toroid- orcircular-shaped synthetic jet actuator surrounding a hollow centralopening. In this embodiment, synthetic jet actuator 60 includes a wallstructure 61 having an unbroken, or continuous inner bounding surface orwall 62 and an unbroken, or continuous outer bounding surface or wall64, both having generally cylindrical profiles. The inner surface 62 andthe outer surface 64 are joined together via a top surface or wall 66and a bottom surface or wall 68. That is, as shown in thecross-sectional view of a portion of synthetic jet 60 in FIG. 6, innerand outer walls or surfaces 62, 64, coupled to top and bottom surfaces66, 68, enclose a volume 70. Orifices 74 pass through surface 62. Thus,a generally toroid-shaped jet 60 is formed having an enclosed volume,chamber or cavity 70 that is separate from the environment 71 externalto the volume 70.

Referring again to FIG. 5, synthetic jet actuator 60 includes one ormore actuator elements, micromechanical devices, or piezomotive devices72 that are positioned on one or all surfaces 62, 64, 66, 68 Innersurface 62, outer surface 64, and top surface 66 are all shown as havingactuators 72 attached thereto. Although actuators 72 are illustrated ascovering only a portion of the respective surfaces 62, 64, 66,embodiments of the invention include one or more actuators 72 configuredto cover the entire respective surfaces 62, 64, 66, 68 on which they areplaced. Actuators 72 may be activated by application of a rapidlyalternating voltage that causes the actuators 72 to rapidly expand andcontract and may be monomorph or bimorph devices. A control system 73 iscoupled to actuators 72, and it is recognized that each actuator 72includes a control system (not shown) for activation. Further, it isrecognized that one control system 73 may be used to actuate more thanone actuator 72.

In embodiments of the invention, actuators 72 may include devices otherthan piezoelectric motive devices such as shape-memory alloys, magneticmaterials, electrostatic materials, hydraulic materials, and ultrasonicmaterials. Thus, in such embodiments, control system 73 is configured toactivate actuators 72 in corresponding fashion. That is, for anelectrostatic material, controller 73 may be configured to provide arapidly alternating electrostatic voltage to actuators 72 in order toactivate and flex surfaces 62, 64, 66, 68 to which actuators 72 areattached. Such additional materials may themselves be configured inmonomorph and bimorph arrangements.

The one or more orifices 74, illustrated as positioned within surface62, may be positioned in order to direct fluid emitting therefrom atdesired locations and at an object (not shown) positioned proximate thesynthetic jet actuator 60. That is, synthetic jet actuator 60 isconfigured to encircle or surround an object or component that couldbenefit from cooling air being directed thereto via the orifices 74, andprovide uniform and circumferential cooling to the object/component byway of the plurality of orifices 74 positioned in surface or wall 62.

Although the synthetic jet actuator 60 of FIG. 5 is illustrated having atoroid shape, the invention described herein is not limited thereto. Oneskilled in the art will recognize that the synthetic jet actuator 60 isnot limited to a toroid shape, but could also be shaped as an oval, asquare, a rectangle, an ellipse, and the like, depending on theapplication, and orifices 74 may be positioned accordingly, depending onthe convective cooling and placement requirements of the application.

Referring now to FIG. 7, a cooling system 80 is shown according to anembodiment of the invention. The cooling system 80 generally comprises aheat sink 82 and one or more synthetic jet actuators 40, such as thatshown and described in FIG. 4. The cooling system 80 uses the syntheticjet actuators 40 in order to cool the heat sink 82, which, in turn, canbe used to cool a heated body or environment, such as a circuit board orpassive device (not shown).

The heat sink 82 of cooling system 80 is constructed of aluminum due tothe relatively high thermal conductivity of aluminum. Alternatively, theheat sink 82 could be constructed from many other types of material, forexample copper or a copper-aluminum combination, depending on theparticular application of the cooling system 80. Typically, it ispreferred that the material of the heat sink 82 be capable ofeffectively conducting thermal energy, e.g. heat. As depicted in FIG. 7,the heat sink 82 is generally formed to have a base 86 and a number offins 88 extending from the heat sink base 86, which are spaced apart soas to define a plurality of channels 90. The base 86 is positioned neara heated body (not shown) to absorb thermal energy therefrom, and theseries of fins 88 protrude out from the base 86 and away from the heatedbody to more effectively dissipate the thermal energy absorbed by theheat sink 82. That is, air or another suitable fluid is passed througheach channel 90 formed between adjacent pairs of fins 88 to dissipatethe heat/thermal energy in the fins 88.

As shown in FIG. 7, the fins 88 are positioned on the base 86 so as togenerally define a hollow, central channel or area 92. That is,according to the embodiment of the invention, the fins 88 are attachedto base 86 in a circular arrangement and spaced from the center of thebase about a central channel 92 clear of fins 88. As further shown inFIG. 7, a pair of synthetic jet actuators 40 is positioned in thecentral channel 92 of heat sink 82 and the actuators 40 are arranged ina stacked configuration and spaced apart from base 86, according to anembodiment of the invention. While two synthetic jet actuators 40 areshown, it is also recognized that a single synthetic jet actuator 40could be placed in central channel 92, or alternatively, that three ormore synthetic jet actuators 40 could be placed in central channel 92.According to an embodiment of the invention, cooling system 80 can beformed as integral system by attaching/securing synthetic jet actuators40 to fins 88 of heat sink 82 by way of a slot 94 formed in fins 88. Itis also envisioned that mounting brackets or mechanisms (not shown)could be implemented for attaching/securing synthetic jet actuators 40within central channel 92 of heat sink 82.

In addition, to be vertically spaced apart in central channel 92, eachsynthetic jet actuator 40 is rotated with respect to adjacent syntheticjet actuators 40. That is, in the embodiment of FIG. 7, the bottomsynthetic jet actuator 40 a is shown as having orifices 54 formed withinouter wall 44 located every 90 degrees about the perimeter 56 of thesynthetic jet actuator 40 a. The top synthetic jet actuator 40 b ispositioned and rotated such that orifices 54 formed within outer wall 44are located every 90 degrees about the perimeter 56 of the synthetic jetactuator 40 b and are angularly offset from the orifices 54 of thebottom synthetic jet actuator 40 a by 45 degrees. The combination of thetop and bottom synthetic jet actuators 40 a, 40 b thus provides orifices54 located every 45 degrees with respect to heat sink 82, thus providingfor the generation and projection of fluid vortices by the synthetic jetactuators 40 at a greater number of locations.

The fluid vortices generated by the synthetic jet actuators 40, andprojected out therefrom through orifices 54, are directed radiallyoutward toward heat sink 82. At the locations of the orifices 54, thefluid vortices pass through the channels 90 of heat sink 82 to provideincreased heat dissipation from the fins 88. According to an embodimentof the invention, and as shown in FIG. 7, the fins 88 of heat sink arevaried in shape. The fins located adjacent the orifices 54, and thatform the channels 90 that receive the fluid vortices generated by thesynthetic jet actuator(s) (i.e., a first portion of the channels), aretriangular-shaped fins 96. The fins that are not located adjacent theorifices 54, and that form the channels 90 that do not receive fluidvortices generated by the synthetic jet actuator(s) (i.e., a secondportion of the channels), are plate-shaped fins 98. Thetriangular-shaped fins 96 are designed to provide enhanced interactionwith the radially outward flow of fluid vortices generated by syntheticjet actuator(s) 40. To further enhance heat dissipation by heat sink 82,the plate-shaped fins 98 promote the entraining of fluid (i.e., air)through channels 90 not receiving fluid vortices from synthetic jetactuator(s) 40. That is, the channels 90 formed by plate-shaped fins 98ingest ambient air in a radially inward direction and into centralchannel 92 of heat sink 82.

Referring now to FIGS. 8A-8C, a cooling system 100 is shown according toanother embodiment of the invention. The cooling system 100 generallycomprises a heat sink 102 and one or more synthetic jet actuators 60,such as that shown and described in FIGS. 5 and 6. The cooling system100 uses the synthetic jet actuators 60 in order to cool the heat sink102, which, in turn, can be used to cool a heated body or environment,such as a circuit board or passive device.

As depicted in FIG. 8, the heat sink 102 is generally formed to have abase 104 and a number of fins 106 extending from the heat sink base 104,which are spaced apart so as to define a plurality of channels 108. Asshown in FIG. 8, the fins 106 are positioned on the base 104 so as togenerally define a hollow, central channel or area 110. That is,according to the embodiment of the invention, the fins 106 are attachedto base 104 in a circular arrangement and spaced from the center of thebase about a central channel 110 clear of fins 106.

As further shown in FIG.8, a pair of synthetic jet actuators 60 arepositioned and configured to encircle or surround heat sink 102 and arearranged in a stacked configuration, according to an embodiment of theinvention. While two synthetic jet actuators 60 are shown, it is alsorecognized that a single synthetic jet actuator could be used, oralternatively, that three or more synthetic jet actuators could be usedto enhance cooling of heat sink. According to an embodiment of theinvention, cooling system 100 can be formed as integral system byattaching/securing synthetic jet actuators to fins 106 of heat sink 102by way of a slot 112 formed in the fins. It is also envisioned thatmounting brackets or mechanisms (not shown) could be implemented forattaching/securing synthetic jet actuators 60 to fins 106 of heat sink102.

In addition, to being vertically spaced apart, each synthetic jetactuator 60 is rotated with respect to adjacent synthetic jet actuators60. That is, in the embodiment of FIG. 8, the bottom synthetic jetactuator 60 a is shown as having orifices 74 formed within inner wall 62located every 90 degrees about an inner perimeter 114 of the syntheticjet actuator 60. The top synthetic jet actuator 60 b is positioned androtated such that orifices 74 formed within inner wall 62 are locatedevery 90 degrees about the inner perimeter 114 of the synthetic jetactuator 60 b, but are angularly offset from the orifices 74 of thebottom synthetic jet actuator 60 a by 45 degrees. The combination of thetop and bottom synthetic jet actuators 60 a, 60 b thus provides orificeslocated every 45 degrees about the heat sink 102, thus providing for thegeneration and projection of fluid vortices by the synthetic jetactuators 60 at a greater number of locations.

The fluid vortices generated by the synthetic jet actuators 60, andprojected out therefrom through orifices 74, are directed radiallyinward toward heat sink 102. At the locations of the orifices 74, thefluid vortices pass through the channels 108 of heat sink 102, exitingthe channels 108 into central channel 110 to provide increased heatdissipation from the fins 106. According to an embodiment of theinvention, and as shown in FIG. 8, the fins 106 of heat sink 102 areplate-shaped, although it is also envisioned that the plurality of fins106 could have a different shape, or be varied in shape such as the finsshown and described in FIG. 7.

It is recognized that additional embodiments of the invention couldincorporate heat sinks having varying configurations. As shown in FIG.9, a heat sink 116 could include a plurality of pin-shaped fins 118mounted on a base 120 and spaced apart to provide channels for fluidflow therethrough. The heat sink 116 is shown as being rectangular inshape, but it is envisioned that a circular, oval, or other geometricshape heat sink could also be implemented. To enhance cooling of anelectronic device (not shown) to which heat sink 116 is mounted,synthetic jet actuators 122 are attached thereto, such as by way ofslots (not shown) formed on fins 118 about an outer perimeter of theheat sink. In the embodiment of FIG. 9, synthetic jet actuators 122 arepositioned/attached on each side of the heat sink 116, although it isalso recognized that synthetic jet actuators 122 could be attached ononly two sides of the heat sink 116. Additionally, it is recognized thata single synthetic jet actuator 122 having an opening in the middlethereof, similar to the synthetic jet actuator shown and described inFIG. 5, could be implemented and positioned about (i.e., surrounding)heat sink 116. Selective operation of the synthetic jet actuator(s) 122would then generate and project fluid vortices out from orifices 123 ofthe synthetic jet actuator(s) 122 to provide fluid flow across the fins118 and enhance cooling.

As shown in FIG. 10, according to another embodiment, a heat sink 124includes a plurality of triangular-shaped fins 126 mounted on a base 120and surrounding and defining a central channel 122. It is alsoenvisioned that heat sinks having a hybrid design could be used, whichhave, for example, a plurality of pin-shaped fins mixed with a pluralityof plate shaped or triangular-shaped fins. Each of these heat sinkscould incorporate and be integrally connected to one or more syntheticjet actuators, such as those shown and described in FIGS. 4-5, so as toform cooling systems according to embodiments of the invention.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

Therefore, according to one embodiment of the invention, a coolingsystem includes a heat sink comprising a base portion and a plurality offins disposed on the base portion and extending vertically outtherefrom, the plurality of fins spaced to define a channel betweenadjacent fins. The cooling system also includes at least one syntheticjet actuator attached to the heat sink, with each of the at least onesynthetic jet actuators comprising a plurality of orifices therein andbeing configured to generate and project a series of fluid vortices outfrom the plurality of orifices and toward at least a portion of thechannels of the heat sink.

According to another embodiment of the invention, a method of cooling aheat generating device includes the steps of providing a heat sinkcomprising a plurality of fins positioned to define a plurality ofchannels in the heat sink, attaching a synthetic jet actuator to theplurality of fins, the synthetic jet actuator having a plurality oforifices formed therein, and generating a series of fluid vortices fromthe synthetic jet actuator. The method also includes the step ofprojecting the series of fluid vortices out from the plurality oforifices of the synthetic jet actuator and toward the plurality of finsand channels of the heat sink, wherein the series of fluid vortices areprojected out from the plurality of orifices toward the plurality offins and channels of the heat sink at a plurality of angles.

According to yet another embodiment of the invention, a cooling systemincludes a heat sink comprising a base portion and a plurality of finsdisposed on the base portion and extending vertically out therefrom todefine a plurality of channels, wherein the plurality of fins arepositioned on the base portion to surround a central channel. Thecooling system also includes a synthetic jet actuator integrallyattached to the heat sink and positioned in the central channel, thesynthetic jet actuator further including a chamber having wallsenclosing a volume, a plurality of orifices formed in the walls, and anactuator element coupled to at least one of the walls to selectivelycause deflection thereof, thereby changing a volume within the chamberso that a series of fluid vortices are generated and projected out fromthe plurality of orifices and toward the plurality of channels of theheat sink.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A cooling system comprising: a heat sinkcomprising a base portion and a plurality of fins disposed on the baseportion and extending vertically out therefrom, the plurality of finsspaced to define a channel between adjacent fins; and at least onesynthetic jet actuator attached to the heat sink, each of the at leastone synthetic jet actuators comprising a plurality of orifices thereinand being configured to generate and project a series of fluid vorticesout from the plurality of orifices and toward at least a portion of thechannels of the heat sink; wherein each of the at least one syntheticjet actuators comprises a toroid shaped synthetic jet actuatorencircling the heat sink, and wherein the plurality of orifices aredispersed about an inner perimeter of the synthetic jet actuator toproject the series of fluid vortices inwardly through the at least aportion of the plurality of channels.
 2. The cooling device of claim 1wherein the plurality of fins are positioned on the base portion todefine a hollow central area in the heat sink.
 3. The cooling device ofclaim 1 wherein the at least one synthetic jet actuator comprises aplurality of synthetic jet actuators positioned in a stacked arrangementso as to be vertically offset.
 4. The cooling device of claim 3 whereinthe plurality of orifices in each of the plurality of synthetic jetactuators are angularly offset from the plurality of orifices in anadjacent synthetic jet actuator.
 5. The cooling device of claim 4wherein the plurality of synthetic jet actuators comprises a pair ofsynthetic jet actuators, with plurality of orifices in one of the pairof synthetic jet actuators being angularly offset 45 degrees from theplurality of orifices in the other of the pair of synthetic jetactuators, such that orifices are located every 45 degrees about theheat sink.
 6. The cooling device of claim 1 wherein the plurality offins comprises a first set of fins having a first shape and a second setof fins having a second shape different from the first shape.
 7. Thecooling device of claim 6 wherein the first set of fins comprisestriangular-shaped fins and wherein the second set of fins comprisesplate-shaped fins.
 8. The cooling device of claim 1 wherein thesynthetic jet actuator comprises: a first plate; a second plate spacedapart from the first plate and arranged parallelly thereto; a wallstructure coupled to and positioned between the first and second platesto form a chamber and including the plurality of orifices therein, thewall structure defining the toroid shape of the synthetic jet actuator;and an actuator element coupled to at least one of the first and secondplates to selectively cause deflection thereof, thereby changing avolume within the chamber so that the series of fluid vortices aregenerated and projected out from the plurality of orifices of the wallstructure.
 9. A cooling device comprising: a heat sink comprising a baseportion and a plurality of fins disposed on the base portion andextending vertically out therefrom to define a plurality of channels;and a toroid shaped synthetic jet actuator attached to the heat sink soas to encircle the heat sink, the toroid shaped synthetic jet actuatorcomprising: a chamber having a wall structure enclosing a volume, thewall structure including an inner bounding wall and an outer boundingwall both having generally cylindrical profiles; a plurality of orificesformed in the inner bounding wall; and at least one actuator elementcoupled to the wall structure to selectively cause deflection thereof,thereby changing a volume within the chamber so that a series of fluidvortices are generated and projected out from the plurality of orificesand toward the plurality of channels of the heat sink.
 10. The coolingdevice of claim 9 wherein the plurality of fins are positioned on thebase portion in a circular arrangement and spaced from a center of thebase portion about a central channel that is clear of fins.
 11. Thecooling device of claim 9 wherein the plurality of orifices of thesynthetic jet actuator are positioned to expel air through at least aportion of the plurality of channels of the heat sink in a radiallyinward direction.
 12. The cooling device of claim 9 further comprisingan additional synthetic jet actuator positioned in a stacked arrangementwith the synthetic jet actuator so as to be vertically offset therefrom.13. The cooling device of claim 12 wherein a plurality of orifices inthe additional synthetic jet actuator are angularly offset from theplurality of orifices in the synthetic jet actuator.